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Allegra-D 12 Hour Allergy & Congestion Side Effects

Generic name: fexofenadine / pseudoephedrine

Medically reviewed by Last updated on May 29, 2023.

Note: This document contains side effect information about fexofenadine / pseudoephedrine. Some dosage forms listed on this page may not apply to the brand name Allegra-D 12 Hour Allergy & Congestion.

Applies to fexofenadine / pseudoephedrine: oral tablet extended release, oral tablet extended release 24 hr.

Serious side effects

Along with its needed effects, fexofenadine/pseudoephedrine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur while taking fexofenadine / pseudoephedrine:

More common

Less common

Incidence not known

Other side effects

Some side effects of fexofenadine / pseudoephedrine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

Incidence not known

For Healthcare Professionals

Applies to fexofenadine / pseudoephedrine: oral tablet extended release.

Nervous system

Common (1% to 10%): Headache, drowsiness, dizziness

Frequency not reported: Nervousness, insomnia, sleep disorders[Ref]


Rare (less than 0.1%): Hypersensitivity reactions (e.g. angioedema, chest tightness, dyspnea, flushing, systemic anaphylaxis)[Ref]


Common (1% to 10%): Nausea[Ref]


Common (1% to 10%): Fatigue[Ref]


Rare (less than 0.1%): Rash, urticaria, pruritus[Ref]


Frequency not reported: Paranoia[Ref]


1. Cerner Multum, Inc. Australian Product Information.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.